A5010281852- Hydrogels: synthesis, properties, applications
- Polymer Surface Interaction Studies
- Advanced Polymer Synthesis and Characterization
- Electrospun Nanofibers in Biomedical Applications
- Block Copolymer Self-Assembly
- Particle Detector Development and Performance
- Material Dynamics and Properties
- Innovative Microfluidic and Catalytic Techniques Innovation
- High-Energy Particle Collisions Research
- Advanced Sensor and Energy Harvesting Materials
- Engineering Education and Pedagogy
- Adhesion, Friction, and Surface Interactions
- Electrowetting and Microfluidic Technologies
- Phase Equilibria and Thermodynamics
- Particle physics theoretical and experimental studies
- Surface Modification and Superhydrophobicity
- Force Microscopy Techniques and Applications
- Natural Fiber Reinforced Composites
- Fiber-reinforced polymer composites
- Nanomaterials and Printing Technologies
- Radiation Detection and Scintillator Technologies
- Membrane-based Ion Separation Techniques
- RNA modifications and cancer
- Heat Transfer and Numerical Methods
- Marine Biology and Environmental Chemistry
Central University of Ecuador
2024
European Organization for Nuclear Research
2023
California State University, Long Beach
2014-2020
The University of Texas at El Paso
2013
University of New Mexico
2001-2009
Cornell University
2006-2008
Harvard University
2008
Sandia National Laboratories
2004
New Mexico Institute of Mining and Technology
2004
The thermally induced hydration transition of surface-grafted poly(N-isopropyl acrylamide) (PNIPAAm) brushes was probed by surface plasmon resonance spectroscopy (SPR) and contact angle measurements. Data are presented for a PNIPAAm brush film with dry thickness ∼50 nm that synthesized atom radical transfer polymerization on the self-assembled monolayer gold. SPR measurements were taken as function temperature in two modes: quasi-static mode, which sample equilibrated at each ∼15 min prior...
The sustained liquid flow of a typical lateral assay can be mimicked by two-dimensional shaped, thin porous membranes, specifically rectangular membranes appended to circular sectors. In designing these fan-shaped devices, we have been aided analytical equations and finite-element simulations. We show both mathematically experimentally how continuous increase in unwetted pore volume causes deviation from traditional imbibition, leads quasi-stationary the element. These results are...
Poly(N-isopropylacrylamide) (PNIPAM) is perhaps the most well-known member of class responsive polymers. Free PNIPAM chains have a lower critical solution temperature (LCST) in water at about 30 °C. This very sharp transition (about 5 °C) attributed to alterations hydrogen-bonding interactions amide groups. Grafted shown promise for creating surfaces. Conformational changes polymer are likely play role some these applications, addition local interactions. In this work we investigated...
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTTemperature-Dependent Conformational Change of PNIPAM Grafted Chains at High Surface Density in WaterH. Yim, M. S. Kent, Mendez, Balamurugan, G. P. Lopez, and SatijaView Author Information Department 1851, Sandia National Laboratories, Albuquerque, New Mexico 87185-1411 Chemical Nuclear Engineering, University Mexico, 87131 NIST Center for Neutron Research, Institute Standards Technology, Gaithersburg, Maryland 20899 Cite this: Macromolecules 2004,...
A novel method for the fabrication of monodisperse mesoporous silica particles is suggested. It based on formation well-defined equally sized emulsion droplets using a microfluidic approach. The contain precursor/surfactant solution and are suspended in hexadecane as continuous oil phase. solvent then expelled from droplets, leading to concentration micellization surfactant. At same time, solidifies around surfactant structures, forming particles. procedure can be tuned produce...
This report describes a convenient method for in situ polymerization of the environmentally responsive polymer, poly(N-isopropylacrylamide) (PNIPAAM), on surfaces azo-initiator-derivatized self-assembled monolayers (SAMs) ω-terminated alkanethiolates gold. In contrast to previous methods initiation free radical from SAM surfaces, this utilizes simple chemistry and commercially available precursors. Carboxylic acid-containing SAMs were derivatized with azo-initiator,...
The evolution of polystyrene–polyisoprene block copolymer self-assembly is studied in coaxially electrospun nanofibers via annealing. leftmost image shows the cross-sectional and longitudinal sections as-spun fibers. Moving to right, a transition morphology can be seen from stacked disk structures for lower annealing temperatures alternating concentric cylinders polyisoprene polystyrene higher times.
Controlling accumulations of unwanted biofilms requires an understanding the mechanisms that organisms use to interact with submerged substrata. While substratum properties influencing biofilm formation are well studied, those may lead cellular or detachment not. Surface-grafted stimuli-responsive polymers, such as poly (N-isopropylacrylamide) (PNIPAAm) release attached cells upon induction environmentally-triggered phase changes. Altering physicochemical characteristics polymeric systems...
The detailed conformational change of poly(N-isopropylacrylamide) (PNIPAM) brushes at high grafting density in D2O was investigated as a function temperature using neutron reflection. PNIPAM chains were grafted surface from gold and silicon oxide surfaces by atom transfer radical polymerization. Whereas single layer profiles observed for temperatures below above the transition region, bilayer narrow range near transition. This nonmonotonic concentration profile with is discussed context...
Formation of various domain shapes in submicron scale fibers poly(styrene-block-isoprene) (PS-b-PI) has been investigated via electrospinning. Monodisperse PS-b-PI block copolymers with 29 and 53 vol % PI were synthesized using two-step anionic polymerization dissolved tetrahydrofuran (THF). Solutions copolymer varying concentrations THF electrospun, average diameters from 200 nm to 5 μm obtained. Small-angle X-ray scattering (SAXS) transmission electron microscopy (TEM) studies revealed...
We modeled the effects of temperature, degree polymerization, and surface coverage on equilibrium structure tethered poly(N-isopropylacrylamide) chains immersed in water. employed a numerical self-consistent field theory where experimental phase diagram was used as input to theory. At low temperatures, composition profiles are approximately parabolic extend into solvent. In contrast, at temperatures above LCST bulk solution, polymer collapsed near surface. The layer thickness effective...
The nucleoli are subdomains of the nucleus that form around actively transcribed ribosomal RNA (rRNA) genes. highly repetitive and nature rRNA genes (rDNA) by polymerase I (Pol I) poses a challenge for DNA repair replication machineries. Here, we profile nucleolar proteome chromatin landscape stalled sites upon rDNA damage tocharacterize early steps response (nDDR). We observed dynamics in nucleolar-nucleoplasmic localization identified stress signatures involving remodeling networks,...
We present molecular dynamics simulations coupled with a dissipative particle thermostat to model and simulate the behavior of symmetric diblock copolymer/nanoparticle systems under simple shear flow. consider two categories nanoparticles, one selective interactions toward blocks copolymer other nonselective both blocks. For we additional variants by changing diameter particle-polymer interaction potential. The aim our study is understand how nanoparticles disperse in block system flow...
Abstract The temperature‐dependent conformational change of poly( N ‐isopropylacrylamide) (PNIPAM) brushes in D 2 O was investigated as a function the molecular weight ( M ) at high grafting density with neutron reflection. PNIPAM chains three different values were grafted same surface from gold by atom transfer radical polymerization. A significant segment concentration profile observed for all samples temperature passed through lower critical solution (∼30 °C), contrast to previous results...
In this work, we examine the interaction between thin films composed of terminally anchored poly(N-isopropyl acrylamide) (PNIPAAm) immersed in water and test surfaces. Understanding force can be important when using PNIPAAm surfaces biotechnological applications such as biological cell cultures. The two novel contributions that are presented here (1) use a recently developed self-consistent field (SCF) theory to predict force-vs-distance profiles, (2) modified polymer scaling estimate wet...
Self-consistent Polymer Reference Interaction Site Model (PRISM) calculations and molecular dynamics (MD) simulations were performed on athermal solutions of linear polymers. Unlike most previous treatments polymer solutions, we explicitly included the solvent molecules. The polymers modeled as tangent site chains molecules taken to be spherical sites having same intermolecular potential sites. PRISM theory was solved self-consistently for both single chain structure correlations a function...
Experimental and numerical studies were carried out to determine the suitability of green natural fiber reinforced polymer (GNFRP) composite plates, fabricated with a bioderived resin matrix embedded hemp fibers acting as tensile transverse reinforcement produced using vacuum infusion process be used for strengthening concrete (RC) beams flexural loading. The experimental study consisted four RC beams: three them control purposes (one plain, two traditional glued carbon (CFRP) composites...
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTUse of Stimuli Responsive Polymers Grafted on Mixed Self-Assembled Monolayers To Tune Transitions in Surface EnergySergio Mendez, Linnea K. Ista, and Gabriel P. LópezView Author Information Department Chemical Nuclear Engineering, The University New Mexico, Albuquerque, Mexico 87131 Cite this: Langmuir 2003, 19, 8115–8116Publication Date (Web):August 13, 2003Publication History Received14 April 2003Revised27 June 2003Published online13 August inissue...
Experimental and numerical studies of sustainable sandwich bio-composites were presented. The developed using plant-based materials. laminated face sheets comprised woven hemp fabric a tree sap–based epoxy, while the core castor oil-based polyurethane foam reinforced with waste rice hulls ashes. Uniaxial compression, tension, three-point flexural bending tests performed. Finite element models developed. Good agreements between experimental numerically simulated responses found. From...
Solutions of polyethylene macromolecules immersed in benzene were modeled with self-consistent polymer reference interaction site model (PRISM) theory. The PRISM integral equations for the solution solved self-consistently intramolecular chain structure and intermolecular solvent correlations at various mole fractions. We found that explicitly considering molecules leads to considerably more short-range radial distribution function polymer, relative without same concentration. long-range...
Abstract A novel method to reconstruct the energy of hadronic showers in CMS High Granularity Calorimeter (HGCAL) is presented. The HGCAL a sampling calorimeter with very fine transverse and longitudinal granularity. active media are silicon sensors scintillator tiles readout by SiPMs absorbers combination lead Cu/CuW electromagnetic section, steel section. shower reconstruction based on graph neural networks it makes use dynamic reduction network architecture. It shown that algorithm able...